1. Field of the Invention
The present invention relates to a reading optical system which is particularly beneficial for a non-scanning type barcode reader in which a predetermined pattern of data, such as a bar code, is imaged on a linear line sensor array to thereby read the data.
2. Description of Related Art
In a conventional non-scanning type bar code reader, a data reading optical system incorporated therein is usually includes of at least two imaging lenses. To effectively make light emitted from a light source incident upon the line sensor array, it is necessary to use imaging lenses whose f-number is small, in view of a relatively low sensitivity of the line sensor (e.g. CCD). An aberration such as a spherical aberration tends to occur when an imaging lens having a small f-number is used. To compensate for the aberration, at least two imaging lenses were used in combination in the prior art.
Increasing the number of lenses, however, prevents the realization of a small and light optical system.